This question is incomplete because it lacks the attached diagram.
Find attached to this answer the appropriate diagram
Answer:
500 square centimeters
Explanation:
From the question above, we are told that the top and bottom of the triangular prism is open.
Hence, the area of the piece of the cardboard is = Lateral Surface Area of the triangular prism
The formula for Lateral Surface Area of a Triangular Prism = Perimeter of the Triangular prism × Height of the Triangular prism.
Perimeter of the Triangular prism = Side a + Side b + Side c
Where Side a = 9cm
Side b = 9cm
Side c = 7 cm
Perimeter of the Triangular prism = 9cm + 9cm + 7cm
= 25cm
Height of the Triangular prism = 20cm
The Lateral Surface Area of the Triangular prism = 25cm × 20cm
= 500cm² or 500 square centimeters.
Since we are told that Lateral Surface Area = Area of the cardboard,
The Area of the cardboard = 500 cm² or 500 square centimeters.